Q: mavericks messages not screen sharing

Hi,

In OS X 10.9.x you can only Screen Share within the app with AIM or Jabber based accounts plus the Bonjour one on a LAN with other Macs

The Yahoo Account is only Text Chat.

iMessages at this version of the OS and Messages app does not Screen Share (despite the Yosemite (OS X 10.10.x) listing the app as version 8 as well).

The Screen Sharing does make use of the Apple Remote Desktop (ARD)

It makes a Audio Only connection on the same ports that plain Video and Audio Only chats do but has  VNC connection alongside.

However rather than being on the ARD port (5900) it uses random ports.

This can be an issue as these random ports tend to be above port 1024.

Most domestic routers have the ports up to this point open (Mail , Web Browsing, FTP and other common apps uses port this low).

If you have changed how ports above this are allowed then this may be the issue.

Using UPnP allows the Computer/App to tell the router which ports  (they close after a period or Non use).

Apple Routers use Port Mapping Protocol which is similar and needs to be turned On in your Airport, Extreme or Time Capsule.

I would also look at DNS servers listed either on the router or the Mac.

The Mac > System Preferences > Network > Advanced button > DNS tab should not list the Router's IP (Check TCP/IP tab). IT may show greyed out version of the one in use on the router (depending if the router allows them to be read.).

7:56 pm      Friday; January 30, 2015

Hi,

In the Router's settings it  should list the IP addresses of the DNS servers of  your ISP.

Copy these across to the Mac  (add each then press enter to be able to ad a second).

I have certainly found that adding the DNS servers directly to the Mac seemed to improve things for me.

Having said that it was when the iMessage servers were "new"  back during Lion and the Beta version.

I have also seen threads where people have come to the conclusion that it is something do do with Monitor size.

I don't remember anything about those being "Solved" with anything specific about working with the resolution.

I was Screen Sharing with someone using two monitors in side by side formation and had no trouble seeing them on my 21" iMac (the layout does make details hard to read as they do become much smaller but they are functional)

In the Video Menu > Connection Doctor are you seeing any Error reported ?

In the Capabilities tab do you see anything that suggests you can't do this ?

8:39 pm      Saturday; January 31, 2015

I just noticed I had this exact problem between my Late 2013 MBP 10.9.5 and a 2014 iMac 10.9.5 as well. Had been using screen sharing via the AIM window just fine up until now. First time using it in a couple months, so don't know when it stopped working. I hear the connection tone, get audio, but no screen sharing window. The dialog box hangs on waiting to connect.

Then I tried between the MBP and another MacBook Air running Mountain Lion, and screen sharing worked just as it has been forever. Bizarre that two 10.9.5 computers can't screen share, but a 10.9.5 - Mountain Lion screen share does work.

Glad to hear you have made progress.

Thanks for letting us know.

8:09 pm      Monday; February 2, 2015

We are experiencing this issue too. Daily use of messages via AIM for screen sharing between Mavericks and Yosemite before latest update. Now it doesn't work as described by original poster. Looks like a bug between OS versions.

Hi,

What have you tried at the moment ?

This is most likely linked to something in the last Security Update.

7:49 pm      Wednesday; February 4, 2015

Hi Ralph,

I haven't tried anything beyond what worked until last week. I suspect we'll need look for an alternative until we can both run Yosemite.

Thanks,

David

HI,

The last Security update looked at the Time Server item in System Preferences > Date and Time.

I would check that again.

If th Firewall Is ON they try turning It Off then On again and also checking the Options button to see the app is allowed.

Try the Keychain Access item in the Utilities Folder and Repairing the Keychain.

9:10 pm      Wednesday; February 4, 2015

Hi Ralph!

Your posts have been very helpful overall, but the problem still remains. I have a client with a Mac Pro running 10.9.5. He was previously able to screen share with no issues. As of about 2-3 weeks ago, he no longer has this capability. The invitation is accepted and the text displays on the screen announcing the session has begun, audio chat is possible, but the screen sharing never starts in earnest, and after a time there is an error for lack of response.

Valid AIM-to-AIM or Jabber (both tried)

No firewall in privacy and security (have toggled on and off and made sure Messages was allowed)

Screen sharing enabled in System Preferences

Caches dumped, iChat container emptied

Permissions repaired

In-place reinstall 10.9.5

Permissions repaired again

Disk repaired

New account created

Second user account created

When Screen Sharing app is accessed directly, it functions across the network.

Same result for all

Access is through Time Warner Cable Business class. Motorola SB6850 modem/router

End user cannot access router settings, so there may be some mysteries in there. The DNS servers are being read from the router and can be seen in Network>Advanced>TCP/IP (Should these be copied in directly, or is the fact that they are visible enough?)

Wirelessly or wired, same result.

At this stage, it is looking like a clean installation of either Mavericks or perhaps Yosemite may be order, unless you can pull a rabbit out of your hat.

Thanks for your time, effort and expertise!

I solved it. No need for a clean install. All I did was upgrade my MBP to Yosemite 10.10.2. The other computer (MBA) is still on Mountain Lion, and our screen sharing now works again. Scrolling back through the previous posts, it looks like most of the issues are from people running 10.9.5 (which is what my MBP was on also), so it's perhaps an issue only with a recent Mavericks security update.

EDIT - That's what I get for writing this before my morning coffee. Screen sharing worked between the Mavericks MBP and Mountain Lion MBA previously. It was upgrading the Mavericks iMac and MBA both to Yosemite that allowed them to screen share again.

Hi,

I do believe that stickhog has the answer in that I think it is something to do with the Security Update 2015-001

This is included in OS X 10.10.2 but is a standalone with earlier versions.

Both the AIM/Jabber in Messages and iChat uses the Apple Remote Desktop engine although the VNC part is on a random port.

In iMessages in Yosemite you can also Screen Share (from the Details "button" top right) but this invokes the Screen Sharing App  and requires you enable Screen Sharing in System Preferences > Sharing - which also needs to be enabled when using it as A Stand Alone app.

Both these methods of using the Apple Remote Desktop engine seem to use the Apple Remote Desktop port for the VNC connection.  (Port 5900)

It is also true that in Yosemite's version if you use the Details button in a chat for AIM and Jabber it also invokes the Screen Sharing App instead of the In-App version.

I think someone has added a feature to the iMessages account in Yosemite (forgetting the app already had the ability) and the security side have tightened up the use of random ports.

I am not sure what to suggest though unless the person has a Time Machine Backup from before the Security Update.  (And a method of grabbing the other changes in the last few weeks)

8:54 pm      Saturday; February 14, 2015

Hi Ralph,

I live in Vancouver, BC Canada and experienced a failure of Screen Sharing around the same time noted by others.  I have been working with Applecare advisors in communication with their software engineers.    I have supported many friends and family on various iMacs and laptops.  What I found was that upgrading to Yosemite fixed the Screen Share via AIM, but only to other Yosemite users.  I went to a friend's computer running Lion and found I could Screen Share with an 2008 vintage 20.5" iMac running Leopard, but not to 2014 21" iMac running Mavericks.  (Until late January I could Screen Share with all these computers (and more) and OS's.  I have tried the various solutions on this forum without success, other than the Yosemite to Yosemite connection.  I am wondering if the Apple software engineers actually have success with screen sharing on their test labs between Yosemite or Mavericks and the older OS's.  Upgrading to Yosemite isn't a solution for everyone.

Bob K